Tuba, bassoon, and double bass are not the most common instruments featured in concertos, where a solo instrument or small group is showcased in conversation with an orchestra. However, there are some such works for these instruments. My playlist includes one for each instrument, plus a "bonus" concerto: originally written for tuba and orchestra but here in a version for euphonium and piano. The composers, Robert Jager, Sofia Gubaidulina, Tan Dun, and Elizabeth Raum, are all accomplished living composers, with different styles and backgrounds.
When exploring repertory for a specific featured instrument, repertory guides and bibliographies can be a useful starting point. Whether published as independent books, maintained on websites, or created as dissertations, repertory guides can give you an organized place to start your search, often including information like duration, difficulty, and unique features to help you explore the landscape.
Guide to the Tuba Repertoire, Second Edition by 
Selected Annotated Bibliography of Compositions for Double Bass by Chinese and Taiwanese Composers by 
A Researcher's Guide to the Bassoon by An Exploration of the Concerto for Bass Tuba by Robert Jager. A Study of its Unique Formal Design, the Elevation of The Solo Tubist, and its Influence on the Solo Tuba Repertoire by Two prolific composers for solo tuba: The complete works of Elizabeth Raum and James Grant by 